| 摘要 |
A device for driving the axial movement of a photographic lens barrel of a camera including a distance adjusting ring having a number of cam portions of similar shape arranged successively on the front end of the ring to cooperate with a follower on the barrel, a ratchet mechanism for turning the ring from the initial or first to the terminal or second position of each cam portion, a rotor arranged in a magnetic field to drive the ratchet mechanism, and a circuit for controlling the current supply to the rotor. After an exposure has been completed, as the ring is further turned in the same direction, when the terminal end of the cam portion moves away from the follower, the lens barrel is set in the initial position of the next cam portion. The rotor control circuit is provided with a switch arranged to open after the lens barrel has moved some distance from the initial position, whereby the circuit is rendered responsive to the closure of the switch for stopping the current supply to the rotor.
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